Serpentine Studies

[Tamela Vandonsel]

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The chemical and physical properties of serpentine and amphibole asbestos are considered in the context of their interaction with tissue of the tracheobronchial tree and lungs. In vitro studies in cultures of several types are evaluated and work with the erythrocyte hemolysis system is reviewed. Although fibers of the two major mineral types differ substantially, it is likely they are modified by secretions and membranes of cells after inhalation to the respiratory tract. Investigations using virgin asbestos might not provide an accurate picture of events in vitro.

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Serpentine-containing rocks, such as serpentinite, are an important cultural and historical material. Serpentinites can be easily worked and are used by many cultures for tool making, decorations, jewelry, ceremonial carvings, and amulets, as well as for magic, such as for protection from snake bites. Nickel, cobalt, chromium, and asbestos (e.g., chrysotile) are largely extracted from serpentine-containing rocks. Several significant treatments of serpentine soils, plants, and other biota, including serpentine as a model for ecological, evolutionary, and applied studies, have been published since 1975. Proctor and Woodell 1975 provides the first review of serpentine ecology, with a focus on factors that limit plant growth on serpentine soils. Brooks 1987 is a comprehensive treatment on serpentine floras from around the world, including individual chapters devoted to geology, soils, and nutritional and elemental stressors plants encounter when growing on serpentine soils. Roberts and Proctor 1992 complements Brooks 1987 in describing soil-plant relations of serpentine from sites in North America, Europe, Africa, Asia, and Australia. Jaffr 1980 provides a review of serpentine plants from endemic-rich New Caledonia, including tissue concentrations of heavy metals in plants found on serpentine soils. Brady, et al. 2005 is an extensive review of studies on the ecology and evolution of serpentine plants, with a particular focus on adaptation and speciation. Although restricted to western North America, Alexander, et al. 2007 is a thorough treatment of the geology, hydrology, and soils as well as the biodiversity (microbes, fungi, animals, and plants) of serpentine soils of California and western North America. The most recent treatment, Harrison and Rajakaruna 2011, is a collection of papers written by experts in their respective fields, asking what serpentine-associated studies have revealed about broader theoretical questions in geology, evolution, and ecology. The chapters on topics relating to earth history, evolution, ecology, and conservation confirm the value of serpentine as a model in multiple disciplines in the natural sciences.

Abby Fullem '16 is spending her summer driving down tiny country roads, working with her hands under the hot Pennsylvania sun, and collecting soil samples at Unionville Serpentine Barrens, a high-priority biodiversity conservation site in Unionville, located in southeastern Pennsylvania.

Funded by the Marian E. Koshland Integrated Natural Sciences Center (KINSC), Fullem, a geology major at Bryn Mawr College, is conducting independent summer research for her upcoming senior thesis project on serpentine soils, which is a rare geological formation.

An hour west of Philadelphia, her research site is a nationally rare ecosystem housing several endangered and rare species of flora and fauna. The Barrens are also unique because they have traces of prehistoric and historical human land uses. Over the past 100 years, however, the land has been shrinking.

"Serpentine is a mineral that, when exposed, is pretty hazardous for most plants to live on," explains Fullem. "Some plants have evolved to live on this soil, which is really cool because it's a direct correlation between the bedrock and the plant life that's on it. This is why I think its interesting: it is geology meeting biology."

Serpentine soil is made up of the mineral serpentine, which is formed in mid-oceanic ridges. It is rarely found on the continent, but there are areas in Maryland, Delaware, Pennsylvania, and northern California where it exists.

Fullem's summer work exemplifies the advantages of the Quaker consortium. Her thesis advisor, Don Barber, works at Bryn Mawr; she's doing GIS mapping this summer with G. Narayanraj, an associate professor at Swarthmore; and she's also working with Roger Latham, a retired Swarthmore professor who has his own conservation lab, Continental Conservation, in Rose Valley, Pa. She is also going to process soil data at Professor Alain F. Plante's lab at the University of Pennsylvania, where she is currently prepping soil for data analysis.

Serpentine soils have long fascinated biologists for the specialized floras they support and the challenges they pose to plant survival and growth. This volume focuses on what scientists have learned about major questions in earth history, evolution, ecology, conservation, and restoration from the study of serpentine areas, especially in California. Results from molecular studies offer insight into evolutionary patterns, while new ecological research examines both species and communities. Serpentine highlights research whose breadth provides context and fresh insights into the evolution and ecology of stressful environments.

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Feature papers represent the most advanced research with significant potential for high impact in the field. A Feature Paper should be a substantial original Article that involves several techniques or approaches, provides an outlook for future research directions and describes possible research applications.

Abstract: Flow field plays an important role in the performance of proton exchange membrane (PEM) fuel cells, such as transporting reactants and removing water products. Therefore, the performance of a PEM fuel cell can be improved by optimizing the flow field dimensions and designs. In this work, single serpentine flow fields with four different land widths are used in PEM fuel cells to study the effects of the land width. The gas diffusion layers are made of carbon cloth. Since different land widths may be most suitable for different reactant flow rates, three different inlet flow rates are studied for all the flow fields with four different land widths. The effects of land width and inlet flow rate on fuel cell performance are studied based on the polarization curves and power densities. Without considering the pumping power, the cell performance always increases with the decrease in the land width and the increase in the inlet flow rates. However, when taking into consideration the pumping power, the net power density reaches the maximum at different combinations of land widths and reactant flow rates at different cell potentials. Keywords: proton exchange membrane fuel cell; flow field; flow field design

The Bay checkerspot butterfly (Euphydryas editha bayensis) was federally listed as threatened in 1987 and deemed extinct at Jasper Ridge in 1998. Decades of intensive study by Prof. Paul Ehrlich and colleagues accumulated more information about the population fluctuations of this butterfly than probably any other non-vertebrate and made it a model system for many questions in conservation. Funded by the Stanford Institute for the Environment, professors from biology, history, soil science, and law are extending this legacy by examining diverse but fundamental issues in restoring any extinct species or lost habitat. The study will help determine whether and how to attempt a reintroduction of Bay checkerspots to Stanford lands.

The Bay checkerspot is restricted to serpentine grasslands, where its native larval host plants (Plantago erecta, Castillejaspp.) and adult nectar plants (Lasthenia californica, Linanthus parviflorus, Layia platyglossa) persist. In many areas, these natives are being out-competed by invasive Eurasian grasses. One goal of the study is to test several methods for creating suitable new habitat. At a disturbed site where the surface soil was scraped away, four soil treatments were applied: a layer of serpentine gravel; magnesium sulfate to shift soil chemistry toward that of serpentine; grazing; or nothing. PhD student Tim Bonebrake sowed a mixture of serpentine and non-serpentine seeds to all treatments and, in spring, will assess their similarity to serpentine grassland.

Other goals are to: 1) analyze the regulatory framework for endangered species and how changes might aid recovery efforts for species like the Bay checkerspot; 2) characterize the genetics of research collections and possible donor populations as a basis for reintroductions; and 3) look at historical changes in the ownership, management, and condition of serpentine grasslands. PhD student Jon Christensen is researching this aspect.

Serpentine, which is a volcanic rock, caused drilling difficulties. Wellbore cavities and pack-off are generally observed problems which causes high torques, pressure build up at SPP and even loss of the well. To minimize well stability problems, modified stresscage system; STIFF DRILL D was improved and achieved in the serpentine section. The serpentine formation is the deepest and longest one in that area as well as in Turkey.

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